Born in Glasgow, Moyes started his career at Icelandic club ÍBV, playing half a season with the youth team in 1978. Moyes enjoyed a career that encompassed playing at a number of clubs, usually as a centre-half, beginning at Celtic, where he won a championship medal and made 24 league appearances, and ending with Preston North End.

Moyes captained Scotland at U18 age group level. He played under former UEFA Technical Director Andy Roxburgh in 1980.

As a player with Cambridge United, Moyes received abuse from teammate Roy McDonough for his religious beliefs; Moyes is a practising Christian. McDonough felt that religion was distracting them from focusing on playing; speaking of Moyes, Alan Comfort and Graham Daniels, he said: “The three of them sat in the changing room with a little black book, discussing their faith, when they should have been getting psyched up for a relegation scrap.” Following a 3–3 draw with Wigan Athletic on 9 March 1985, McDonough, who was 26 years old at the time, states that he “battered” Moyes for not putting sufficient effort into the game.

While playing for Shrewsbury Town in 1987, Moyes began coaching at the nearby private school, Concord College, on the recommendation of Jake King as a way to supplement his wages. Moyes later made over one hundred appearances for Dunfermline Athletic FC between 1990-93, including a starting appearance in the 1991 Scottish League Cup Final.

Everton managed to sustain a good run of form and avoided relegation, which was a genuine threat when he was originally appointed. Despite having a history and list of honours only surpassed in English football by Liverpool, Arsenal and Manchester United, the past decade had not been a successful time for the Toffees, with an FA Cup win in 1995 and a sixth-place finish in 1996 being about the only bright spots for the club that side of 1990.

Moyes made over 550 league appearances in his career before becoming a coach at Preston, working his way up to assistant manager before eventually taking over as manager in 1998.

Moyes took over as Preston North End manager in January 1998, replacing Gary Peters as the club struggled in Division Two and were in danger of relegation. He had spent much of his playing career preparing for management, taking coaching badges at just 22 years of age and compiling notes on managers he had played under, their techniques and tactics. Preston avoided relegation at the end of the 1997–98 season and reached the Division Two play-offs the following season, where they were beaten by Gillingham at the semi-final stage.

The following season, Moyes guided Preston to the Division Two title and a promotion to Division One. An even greater achievement perhaps was to steer Preston into the Division One play-offs the season after that, with largely the same squad. Preston lost 3–0 to Bolton Wanderers in the 2001 Football League First Division play-off Final, missing out on promotion to the Premier League. One month later, Moyes signed a new five-year contract with the club. Towards the end of the following season, he left for Everton, to take over from fellow Scotsman Walter Smith in March 2002. Moyes took charge of Preston for 234 matches, of which his team won 113, drew 58 and lost 63.

Moyes joined Everton on 14 March 2002 and at his unveiling press conference, declared that Everton were ‘The People’s Club’ on Merseyside. He said:

Moyes prepared for his first full season in charge at Everton by signing Chinese international Li Tie, Nigerian defender Joseph Yobo and goalkeeper Richard Wright and released older players such as Jesper Blomqvist and David Ginola. On 12 April 2003, Moyes was sent to the stands during a game against West Bromwich Albion by referee Steve Bennett for using foul and abusive language and for improper behaviour. Everton were edged out of qualification for the following season’s UEFA Cup on the last day of the season by Blackburn Rovers, following a defeat by Manchester United, and finished seventh in the league. Moyes was awarded LMA Manager of the Year for the first time, to go with the Premier League Manager of the Month award for November 2002, when the Toffees had been in the Champions League places.

For the 2003–04 season, Moyes signed Kevin Kilbane from Sunderland, James McFadden from Motherwell, Nigel Martyn from Leeds United and Francis Jeffers returned on loan from Arsenal. Poor results followed though and Everton did not win a game in 2004 until 28 February. A confrontation between Moyes and Duncan Ferguson at Everton’s training ground was said to be symptomatic of the problems at the club. Everton finished 17th with 39 points, the lowest total in the club’s history (although survival had been confirmed some time earlier), just avoiding relegation.

In 2005, Moyes received an honorary fellowship from Myerscough College near Preston. In December 2017, Moyes received another honorary fellowship from the University of Central Lancashire.

At the end of the transfer window January 2009, Moyes brought in Brazilian international striker Jô on loan from Manchester City. On 14 October 2008, Moyes agreed to extend his Goodison Park stay by a further five years. On 19 April 2009, Moyes led his team to an FA Cup semi-final victory over Manchester United, after a penalty shoot-out, to reach the final for the first time since 1995. In what would be Everton’s only appearance in a final during Moyes’s time at the club, Everton were beaten 2–1 by Chelsea despite taking a lead through Louis Saha in the opening minute.

In the summer of 2009, Moyes sold Joleon Lescott to Manchester City for £22 million, after a saga that lasted for the entire transfer window. With the money from the Lescott sale, Moyes brought in Johnny Heitinga, Sylvain Distin and Diniyar Bilyaletdinov. He also re-signed Jô on a season-long loan and Lucas Neill on a free transfer. Moyes was named as Premier League Manager of the Month for January 2010 after three wins and a draw. Moyes’ took charge of his 600th match as a manager on 6 February 2010 in the Merseyside Derby against Liverpool which resulted in a 1–0 defeat. Everton ended the season in eighth place, failing to qualify for Europe for the first time in four years despite a run of only two defeats in their last 24 league games.

On 14 May 2010, Moyes revealed he would be interested in taking up the Celtic job in the future; that job did indeed become vacant at the end of the 2009–10 season with the departure of Tony Mowbray, but Moyes did not put his name forward for the vacancy and Neil Lennon was appointed instead. In August 2010, Moyes dismissed speculation linking him with the manager’s job at Aston Villa left vacant by the resignation of Martin O’Neill.

In September 2010, Moyes admitted an improper conduct charge in relation to his behaviour towards referee Martin Atkinson following a 3–3 draw with Manchester United. He was fined £8,000 with his assistant Steve Round also admitting to the same charge.

He is a supporter of the Labour Party and in 2010 backed Andy Burnham to be leader in the Labour Party leadership election.

During the 2010 FIFA World Cup in South Africa, Moyes provided some commentary for selected matches for BBC Radio 5 Live. Moyes co-owns the racehorse Desert Cry, which was trained by Ginger McCain.

In January 2012, Moyes became the fourth manager, after Alex Ferguson, Arsène Wenger and Harry Redknapp, to record 150 wins in the Premier League. He celebrated his 400th Premier League game in November 2012 with a 2–1 win against Sunderland.

On 9 May 2013, following Ferguson’s retirement at Manchester United and with his own contract expiring at the end of the season, Moyes informed Everton that he would leave the club to succeed Ferguson. Three days after being named as Ferguson’s successor at Manchester United, Moyes took charge of his last game with Everton at Goodison. He received a guard of honour by his own players prior to the post-match lap of appreciation, and Everton fans held banners with messages such as “Goodbye and Good luck”, and “Thanks for the memories”. On his reception, Moyes stated, “It was really emotional. All the stewards were standing clapping me when I came in and I didn’t know what to do. I am gobsmacked and thankful and humbled for what the people of Everton have shown me today”.

Moyes signed a six-year contract with Manchester United, and officially took up his managerial position on 1 July 2013. Moyes had been hand-picked as manager by Sir Alex Ferguson and after his appointment a banner reading “The Chosen One” was displayed at Old Trafford. His first unofficial game as United manager ended in defeat as Teeratep Winothai scored the only goal for Singha All Stars in Bangkok on 13 July 2013. On 11 August 2013, he won his only trophy with Manchester United in his first official game, a 2–0 win over Wigan Athletic in the FA Community Shield. It meant he became the first United manager in history to win a trophy outright in his first season in charge. Less than a week later, he won his first league game in charge of the club, opening the season with a 4–1 victory against Swansea City, but after that, United suffered their worst ever start to a Premier League season, leading the start of his reign to be described as “calamitous” following a 1–0 defeat at Liverpool, a 4–1 defeat at Manchester City and a 2–1 home defeat by West Bromwich Albion (United’s first defeat to West Brom at home since 1978), with several journalists stating the pressure was now on despite it being early in his reign. On 2 September 2013, Moyes signed Marouane Fellaini on a four-year contract, with the option of extension of another season, reuniting with his former player in a £27.5 million deadline day deal.

In January 2014, United were knocked out of the FA Cup in the third round by Swansea City, losing 2–1 at home (Swansea’s first ever win at Old Trafford), and lost in the semi-final of the Football League Cup, with Sunderland winning a penalty shoot-out. In February, United lost 2–1 at Stoke (Stoke’s first win over United in 30 years). Following consecutive 0–3 home defeats against Liverpool and Manchester City, a flypast was staged by United fans with the banner displaying “Wrong One – Moyes Out” in seven-foot high lettering during a home match against Aston Villa in March. After the match, which United won 4–1, Moyes said the majority of fans had been “very supportive” of him. The club reached the quarter-final stage of the Champions League, after beating Olympiacos, but were defeated 4–2 on aggregate by Bayern Munich.

On 24 January 2014, Chelsea had accepted a transfer offer from Manchester United for Juan Mata to travel to Manchester to undergo a medical, after the player said he was “really happy to go”. Manchester United confirmed later in the day that a transfer fee had been agreed, but that the deal was still contingent on Mata agreeing personal terms and passing a medical. The transfer was completed the following day, with Manchester United paying Chelsea a then club record fee of £37.1 million, with Mata signing a contract until the summer of 2018.

On 20 April 2014, United lost 2–0 at Everton (the first time Everton had beat United home and away in 44 years). Two days later, United announced that they had sacked Moyes. Moyes was in charge of United for 10 months, the third-shortest managerial stint in United history and the shortest in 82 years, despite calls from several respected ex-Manchester United players such as Denis Law and David Beckham calling for Moyes to be given more time at the club. At the time of his sacking, United were seventh in the Premier League table, 13 points behind fourth-placed Arsenal with four matches remaining, ensuring United would fail to qualify for the Champions League for the first time since 1995 and finish outside of the top three for the first time in Premier League history. Moyes had won 5 points from a possible 24 against Liverpool, Chelsea, Manchester City, and Arsenal (the top four at the time of sacking). He was replaced in the interim by long-serving player Ryan Giggs and permanently by Louis van Gaal. Moyes was awarded £5 million in compensation following the sacking.

On 10 November 2014 Moyes was appointed as the new manager of La Liga club Real Sociedad on an 18-month deal after the dismissal of Jagoba Arrasate, with the team lying in 15th in the table. His managerial debut was an away league match against Deportivo La Coruña on 22 November, which ended in a goalless draw. Six days later, in his first home match at Anoeta, he earned his first victory as the club’s manager, Carlos Vela scoring a hat-trick in a 3–0 win over Elche. On 4 January 2015, Moyes led Sociedad to a 1–0 win over Barcelona, a result which journalists compared to his management of Everton and contrasted with his results at Manchester United. Ten days later, in a 2–2 home draw against Villarreal which eliminated his team from the Copa del Rey, Moyes was sent to the stand and later given a two-match touchline ban for arguing over an offside decision.

He was sacked on 9 November 2015 after coming under increasing pressure due to a poor start to the season.

On 23 July 2016, Moyes was appointed as the replacement for Sam Allardyce as manager of Sunderland, returning to the Premier League for the first time since his sacking as United boss in April 2014.

On 3 April 2017 it was revealed that Moyes had made a controversial remark after a post-match interview after Sunderland’s goalless draw with Burnley on 18 March. After the interview with the BBC’s Vicki Sparks, while the microphone was still audible, Moyes, said: “It was getting a wee bit naughty at the end there so just watch yourself. You still might get a slap even though you’re a woman. Careful the next time you come in”. Moyes apologised for the incident. The FA wrote to Moyes to ask for his observations on the incident. In June that year, he was fined £30,000 for the comments, a decision that was upheld by an independent panel the following month.

Sunderland were confirmed to be relegated to the EFL Championship for the first time in ten years on 29 April 2017, after a 1–0 loss to Bournemouth, marking the first relegation of Moyes’ career. After the match, he stated that he would like to remain as manager. However, on 22 May, one day after the end of the Premier League season, Moyes resigned.

Moyes was appointed manager of West Ham United on 7 November 2017, with the team in the relegation zone. Moyes marked his first game in charge of West Ham, and his 500th Premier League game, with a 2–0 loss away to Watford on 19 November. On 9 December, he won as Hammers manager for the first time, Marko Arnautović scoring the only goal of a win over reigning champions Chelsea at the London Stadium. On 13 January 2018, West Ham registered a 4–1 win away to Huddersfield, which became Moyes’s 200th victory as a Premier League manager, he became only the fourth to reach this milestone, after Sir Alex Ferguson, Arsène Wenger and Harry Redknapp. Following a 2–0 win at Leicester City on 5 May 2018 and with two games remaining of the season, Moyes managed West Ham to Premier League survival for the 2017–18 season. His six-month deal with West Ham expired on 13 May 2018 and he left the club on 16 May 2018 after he was not offered a new contract.

On 29 December 2019, Moyes returned to his previous position as the manager of West Ham United on an 18-month contract. He replaced Manuel Pellegrini, who had left them in 17th in the Premier League table, one point above the relegation zone. Speaking about his return to West Ham, Moyes said, “I think there’s only two or three managers with a better Premier League win record. That’s what I do, I win. I’m here to get West Ham wins and get them away from the bottom three.”

His first game on return resulted in a 4–0 win, against A.F.C. Bournemouth, in the Premier League on 1 January 2020. West Ham finished in 16th place in the Premier League with 39 points, their lowest points tally since 2010-11 when they gained 33 points and finished bottom. Moyes’ 19 games in charge produced 20 points, one more than the previous 19 games managed by Manuel Pellegrini.

In April 2020, during the COVID-19 pandemic, Moyes accepted a 30% cut to his salary as West Ham looked to retain jobs allowing them to pay 100% of non-playing staff salaries. He left London during the pandemic and worked in his home village in Lancashire delivering fruit and vegetables to those in need. On 22 September 2020, shortly before an EFL Cup fixture against Hull City, Moyes and players Josh Cullen and Issa Diop tested positive for COVID-19 and left the ground before the game. His place was taken by Alan Irvine as West Ham won 5-1. He then returned a second positive test three days later.